User:Trager2/Prurigo nodularis

Lead:

Prurigo nodularis (PN), also known as nodular prurigo, is an inflammatory skin disorder characterized by pruritic (itchy), nodular lesions, which commonly appear on the trunk, arms and legs. Patients often present with multiple excoriated nodules caused by chronic scratching. Although the exact cause of PN is unknown, PN is associated with other dermatologic conditions such as untreated or severe atopic dermatitis and systemic causes of pruritus including liver disease and end stage kidney disease. The goal of treatment in PN is to decrease the itch sensation. PN is also known as Hyde prurigo nodularis, or Picker's nodules.

Signs and symptoms[edit]

 * Nodules are discrete, generally symmetric, hyperpigmented and firm. They are greater than 0.5 cm in both width and depth (as opposed to papules which are less than 0.5 cm).
 * The nodules of PN can appear on any part of the body, but generally are found in areas where patients are able to reach to scratch. Patients can exhibit a 'butterfly sign' in which nodules are absent in the mid upper back.
 * Nodular lesions are often excoriated from persistent scratching.
 * The nodules in PN are extremely itchy, this sensation can have an impact on patients perceived quality of life
 * Nodule pattern can be follicular.

Causes[edit]
The exact cause of prurigo nodularis is unknown, however, it is thought to be induced by other dermatologic conditions such as severe atopic dermatitis, Becker's nevus, and linear IgA disease. PN is also associated with systemic causes of pruritus such as cholestasis, thyroid disease, polycythemia vera, uremia, Hodgkins lymphoma, HIV, liver failure, and kidney failure. Psychiatric illnesses have been considered to induce PN, although more recent research has refuted a psychiatric cause for PN. Patients report an ongoing battle to distinguish themselves from those with psychiatric disorders, such as delusions of parasitosis and other psychiatric conditions.

Diagnosis[edit]
Diagnosis is based on visual examination and the presence of itching for greater than 6 weeks duration. A skin biopsy is often performed to exclude other diseases. Lesion biopsies usually show light inflammation, sometimes with increased numbers of eosinophils. A culture of at least one lesion will rule out staphylococcus infection, which has been significantly linked to atopic dermatitis.

References:

Leis M, Fleming P, Lynde CW. Prurigo Nodularis: Review and Emerging Treatments. Skin Therapy Lett. 2021;26(3):5-8.